Compressão pneumática intermitente como estratégia placebo: análise da magnitude do efeito e responsividade da intervenção

Abstract

Ischemic preconditioning (IPC), when applied in the sports context, has gained significant attention as an emerging ergogenic aid in recent years. Its appeal lies in its non-invasive, simple, and practical nature, allowing for application both before and after exercise. However, despite nearly 25 years of research on its ergogenic effects, a consensus regarding its effectiveness in enhancing performance remains elusive. Some argue that the heterogeneity of results may stem from a potential placebo effect associated with its use, although this possibility has not been adequately explored in the existing literature. Given its inherent presence in the sports context, the analysis of new potential ergogenic aids should take into careful consideration the placebo effect. Therefore, the main aim of this thesis was to investigate the potential placebo effect associated with IPC intervention. Additionally, it aimed to provide an up-to-date perspective on the real effect of IPC on sports performance. To achieve these objectives, the thesis comprised three studies. The first study aimed to investigate the efficacy of IPC intervention in improving performance and discern whether it is primarily influenced by a placebo effect. The study focused on evaluating the effects of the simultaneous application of IPC and placebo conditions on resistance exercise (RE) performance, taking into account the potential influence of subjects' modified expectations and tactile perception of the cuff. Nine healthy male participants, experienced in RE, were included in the study. The results did not indicate any superiority of the IPC intervention in enhancing performance, suggesting the involvement of a central placebo component. For the second study, the aim was to broaden the perspective on the placebo response associated with the intermittent pneumatic occlusion maneuver. This was achieved by manipulating subjects' expectations in different contexts: positive or negative, while administering a sham IPC intervention. The study included thirty-five healthy men with experience in RE. The results revealed a significant influence of the generated expectations on the maximum number of repetitions. Specifically, the positive manipulation led to an increase in repetitions, while the negative manipulation resulted in a reduction. These findings provide compelling evidence of the substantial psychological contribution underlying the effectiveness of the intermittent pneumatic occlusion maneuver. The purpose of the third study was to provide an updated state-of-the-art analysis of the IPC intervention in exercise capacity and athletic performance. In this systematic review with meta-analysis, sixty-eight studies were analyzed quantitatively. The study examined three main comparisons: IPC versus Placebo, IPC versus Control, and Placebo versus Control. The analysis revealed that the IPC intervention did not demonstrate superior performance improvements compared to the placebo condition for most of the assessed outcomes. Conversely, the findings revealed that the placebo condition exhibited a considered impact on performance compared to the control condition, highlighting its potential effect on the outcomes. In conclusion, based on the multifactorial nature of the findings and the lack of superiority associated with the IPC intervention, its use as an ergogenic strategy remains questionable.